1. Field of the Invention
The present invention relates to a liquid crystal display device.
2. Description of the Related Art
Conventionally, liquid crystal display devices to be used for a television set or the like include a liquid crystal display device in which an electric field is formed between a common electrode and a pixel electrode, and liquid crystal is driven with the electric field.
In such a liquid crystal display device, the pixel electrode and the common electrode are laminated one on top of another via an insulating layer. One of the electrodes is provided with slits, and the other of the electrodes is formed into a uniform plane shape without a space, that is, formed into a so-called solid shape.
As the electrode provided with the slits, there is a comb-shaped electrode in which one end of both end portions of each slit is closed and the other end thereof is opened, or an electrode in which both the end portions of the slits are closed. Further, multi-domain type liquid crystal display devices include a liquid crystal display device in which the slits of such electrodes are bent.
By the way, in the liquid crystal display devices, there are cases where, when the electric field is formed between the common electrode and the pixel electrode to drive the liquid crystal, a region in which a transmittance becomes low (hereinafter, referred to as domain) is generated because liquid crystal molecules are aligned in a direction different from a desired direction.
For example, in a case of a structure in which the electric field is generated by the above-mentioned electrode provided with the slits and a uniform plane-shaped electrode without a space, the domain is generated at end portions of the slits in a long-side direction thereof and in a vicinity thereof, or at bent portions of the slits and in a vicinity thereof. Such a liquid crystal display device has a problem in that the transmittance reduces due to the domain generated in an opening portion of a pixel, which causes reduction in brightness. To address this problem, it is conceived to increase the output of an illumination device (backlight unit) to increase the brightness, but this method has a problem in that power consumption increases.
Meanwhile, there has been proposed a liquid crystal display device in which light reflected on a rear surface of a liquid crystal display panel is reused, to thereby increase the brightness (for example, see Japanese Patent Application Laid-open No. Hei 06-138453). In the liquid crystal display device described in Japanese Patent Application Laid-open No. Hei 06-138453, a light reflection film is provided to a non-opening portion which does not influence the transmittance, such as a thin film transistor and a black matrix. Light is reflected by the light reflection film toward the illumination device (backlight unit), and the light is reflected toward the liquid crystal display panel again, to thereby reuse the light.
In the liquid crystal display device described in Japanese Patent Application Laid-open No. Hei 06-138453, in a case where the light reflection film to be provided to the non-opening portion is arranged on an inner side of a polarizing plate, when the light returning to the illumination device (backlight unit) is reflected by the illumination device (backlight unit) and returns to the liquid crystal display panel again, a polarization state of the light is changed, and hence most part of the light is absorbed in the polarizing plate, which reduces the brightness increase effect. Further, in a case where the light reflection film is arranged on an outer side of the polarizing plate, a positional relationship between the light reflection film and the non-opening portion deviates due to parallax, which reduces the brightness increase effect. Further, no consideration is given to the low-transmittance region in the opening portion, such as the domain.